An operation menu set in an input device generally requires a driver to perform more than one operation. For example, in order to change a setting of an option, a user is required to select a target option from multiple options, determine the selection of the target option, and change detailed settings of the determined option. Thus, operations for selecting the target option and change the detailed settings of the selected option are required to be carried out by the user. As a configuration having an operation menu listing multiple operations each of which requires more than one operation by the user, an operation input device capable of detecting two types of gestures is described in, for example, Patent Literature 1. With the operation input device in Patent Literature 1, a driver performs a selection operation to select an operation mode with a first type gesture and performs a changing operation to change a parameter of the selected operation mode with a second type gesture.
According to a configuration of Patent Literature 1, two types of gestures made by the driver need to be distinguished from each other by the operation input device. Hence, a gesture of each type requires complex hand motion. It thus becomes difficult for the driver to make a gesture while holding a steering wheel and the driver has to move his hand off the steering wheel for a considerable time. In addition, because the driver is required to make complex gestures of two types, the driver's concentration may be distracted from vehicle driving for making the predetermined complex gestures.